Question

The length of latus-rectum of the parabola x² + 2y = 8x - 7 is ______.

Options

• 4

• 8

• 6

• 2

Answer 1

The length of latus-rectum of the parabola x² + 2y = 8x - 7 is 2.

Explanation:

We have,

x² + 2y = 8x - 7

x² - 8x = - 2y - 7

x² - 8x + 16 = - 2y - 7 + 16

(x - 4)² = - 2y + 9

(x - 4)² = - 2(y - 9/2)

∴ Length of latus rectum = 2